I. Technical field
The invention relates in general, to a thread control device for selectively controlling an oscillating transverse movement of a thread, in particular a warped thread of a weaving machine, having at least one lifting device which can be driven in an oscillating fashion, a carrier for a thread and at least one control means which can be actuated to bring the thread selectively into engagement with the carrier.
II. Background Information
There are many known thread control devices, particularly in shedding mechanisms, for optionally controlling an oscillating transverse movement of a thread.
In a first type of such thread control devices, the threads are controlled indirectly, the thread being moved only when it is selected. For this purpose, threads are firmly drawn into eyelets of healds and guided, the healds being moved in a programmed fashion via connecting means with the aid of upstream jacquard machines, heald looms and treading machines. It is easy to establish in this case that selective movement of the thread requires a multiplicity of components and a large stroke for them, and this necessarily has a very negative influence in many regards. Thus, in particular, the speed of the shedding mechanism is very limited because of the high mass forces. Further marked disadvantages of the known thread control devices are, for example, a high wear level, strong vibration, loud noise, a large space requirement because of the complicated devices, and poor ergonomics and the like. Finally, they are also relatively expensive, because of the complicated design.
A second type of such thread control devices is disclosed in U.S. patent application Ser. No. 09/043,542 filed Mar. 19, 1998. This thread control device has a lifting device, which can be driven in an oscillating fashion, having at least one carrier for the thread, as well as at least one control means which can be actuated by means of an actuator in order to bring the thread selectively into engagement with the carrier of the lifting device. These control means are arranged, assigned directly to the carrier, on the lifting device and are moved to go up and down with the latter. This results in various disadvantages. Since the lifting device must contain not only the carrier but, in particular, also the control means and the actuator, it has a relatively large volume. This thread control device is ill-suited to a weaving machine with a high warp count. Moreover, the moving parts are of relatively large mass and must, in addition, be moved over the entire stroke of the lifting device. The co-movement of the actuator further requires a moving interface with the supply of power and program data, which is relatively complicated, expensive and prone to wear. A thread has to be drawn in very carefully, in order to prevent parts from being bent, and thus a functional failure associated with corresponding repair costs. Despite good accessibility, it is time consuming and costly to draw in a thread. Finally, because of the relatively high mass forces and the sensitivity of the electronic system integrated into the moving parts, such a thread control device can be operated only at a relatively low speed.